A systematic review on the use of TENS for those with fibromyalgia syndrome (FMS) shows that the number needed to treat (NNT) compared to placebo was 4.5 which believe it or not is better than pharmaceutical drugs used to manage FMS as their NNTs vary from 6 to 9! Of course other than potential skin irritation, TENS has no other adverse effects, compared to pharmaceutical interventions.
“Treatment with TENS is effective for reducing pain in people with fibromyalgia” – Systematic review Garcia et al 2019
Yet the Cochrane review concludes, “There was insufficient high-quality evidence to support or refute the use of TENS for fibromyalgia.” – Johnson et al 2017
As much as I don’t support the use of tingling machines by PTs in a clinical setting, I am not against the trial use of a home TENS unit to be used for 2 hours a day, for 4-8 weeks. If benefit is seen, great; if not, abandon it.